Novel asymmetric membranes consisting of polyethersulfone (PES) as the membrane matrix and poly (ethylene oxide) (PEO)-containing block-copolymer F68 as the versatile modifier are prepared via surface segregation. The membranes are then characterized by scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectra, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and electronic tensile machine. The surface segregation of CO2-philic EO groups greatly enhance CO2 solubility in the membrane surface. Moreover, the increased PES chain mobility by the interaction between PES and F68 enhances the gas diffusivity in the bulk active layer. The membrane with 20 wt% F68 exhibits CO2 permeance increment of 210% and CO2/N-2 selectivity increment of 105%. Pressure, temperature and long term tests are conducted to get more integrated understanding of membrane performance. The strategy of constructing asymmetric membranes by surface segregation holds great promise for efficient carbon capture. (C) 2015 Elsevier B.V. All rights reserved.